In situ stent formation

ABSTRACT

Apparatus and methods for delivering stents and other prostheses to body lumens include a prosthesis forming and deploying mechanism carried at the distal end of a catheter shaft. The mechanism is adapted to form and deploy prostheses of a variable length, and to form and deploy multiple prostheses during a single interventional procedure.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to medical devices and methods.More particularly, the present invention relates to apparatus andmethods for in situ formation of luminal prostheses within a body lumen,such as a blood vessel.

Coronary artery disease is the leading cause of death and morbidity inthe United States and Western society. In particular, atherosclerosis inthe coronary arteries can cause myocardial infarction, commonly referredto as a heart attack, which can be immediately fatal or, even ifsurvived, can cause damage to the heart which can incapacitate thepatient.

While coronary artery bypass surgery can be an effective treatment forstenosed arteries resulting from atherosclerosis or other causes, it isa highly invasive, costly procedure, which typically requiressubstantial hospital and recovery time. Percutaneous transluminalcoronary angioplasty, commonly referred to as balloon angioplasty, isless invasive, less traumatic, and significantly less expensive thanbypass surgery. Heretofore, however, balloon angioplasty has not beenconsidered as effective a treatment as bypass surgery. The effectivenessof balloon angioplasty, however, has improved significantly with theintroduction of stenting which involves the placement of a scaffoldstructure within the artery which has been treated by balloonangioplasty. The stent inhibits abrupt reclosure of the artery and hassome benefit in inhibiting subsequent restenosis resulting fromhyperplasia. Recently, experimental trials have demonstrated that thecoating of stents using anti-proliferative drugs, such as paclitaxel,can significantly reduce the occurrence of hyperplasia in angioplastytreated coronary arteries which have been stented with the coatedstents. Stents are also used to treat blockages of peripheral bloodvessels, including those in the neck, head, abdomen and legs.

While the combination of balloon angioplasty with drug-coated stentsholds great promise, significant challenges still remain. Of particularinterest to the present invention, the treatment of extended ordisseminated disease within an artery remains problematic. Most stentshave a fixed length, typically in the range from 10 mm to 30 mm, and theplacement of multiple stents to treat disease over a longer lengthrequires the use of multiple stent delivery catheters. Moreover, it canbe difficult to stent an angioplasty-treated region of a blood vesselwith the optimum stent length.

For these reasons, it would be desirable to provide improved stents,stent forming apparatus and methods, stent delivery systems, stentingmethods, and the like, for the treatment of patients having coronaryartery disease, as well as other occlusive diseases of the vasculatureand other anatomical structures. In particular, it would be desirable toprovide stents, stent forming apparatus and methods, stent deliverysystems, and methods for the treatment of disseminated and variablelength stenotic regions within the vasculature. For example, it would bedesirable to provide a practical method which permits a physician totailor the length of the stent delivered to a treatment location whilethe delivery apparatus is adjacent to the treatment location, ratherthan having to deliver a stent having a predetermined length. Morespecifically, it would be desirable to provide apparatus, systems, andmethods for facilitating the delivery and in situ formation of stentsand other prostheses to blood vessels or other target body lumens. Suchapparatus, systems, and methods should be suitable for delivery and insitu formation of individual stents or prostheses having lengths rangingfrom very short (typically as short as 3 mm or shorter) to relativelylong (typically as long as 100 mm or longer), which lengths may bedetermined for a subject stent during the course of the stent deliveryand in situ formation. Such apparatus, systems, and methods should alsobe capable of delivering and forming multiple individual stents atmultiple treatment locations during a single interventional procedure(i.e., without fully withdrawing the catheter from the patient). Atleast some of these objectives, and others, will be met by theinventions described hereinafter.

2. Description of the Background Art

U.S. Pat. No. 6,258,117 B1 describes a stent having multiple sectionsconnected by separable or frangible connecting regions. Optionally, theconnecting regions are severed after the stent structure has beenimplanted in the blood vessel. U.S. Pat. Nos. 5,571,086; 5,776,141; and6,143,016 describe an expandable sleeve for placement over a ballooncatheter for the delivery of one or two stent structures to thevasculature. U.S. Pat. No. 5,697,948 describes a catheter for deliveringstents covered by a sheath.

U.S. Pat. No. 5,059,211 describes an expandable absorbable stent. U.S.Pat. No. 5,147,385 describes methods for using stents that are hollow,cylindrical structures made of synthetic substance that becomes plasticand malleable in a temperature range of from 45° to 75° Celsius. U.S.Pat. Nos. 5,213,580 and 5,947,977 describe processes for paving orsealing interior surfaces of body vessels or organs by entering theinterior of the vessel or organ and applying a polymer to the interiorsurfaces thereof. U.S. Pat. No. 5,670,161 describes an expandable,biodegradable stent. U.S. Pat. No. 6,607,553 describes an expandablestent that is coated with a radiation-absorbing material. U.S. Pat. No.6,039,757 describes a fenestrated stent formed in a body lumen. U.S.Pat. No. 6,623,519 describes an endoluminal stent containing a hollowpassageway for circulating fluids to treat vascular walls affected withmalignant growths or experiencing restenosis.

BRIEF SUMMARY OF THE INVENTION

The present invention provides methods and apparatus for deploying aprosthesis in a lumen. The methods and apparatus are particularlyadapted for use in stenting of body lumens, and more typically stentingcoronary arteries. The methods and apparatus will also find significantuse in the peripheral vasculature, the cerebral vasculature, and inother ducts, such as the biliary duct, the fallopian tubes, and thelike. The terms “stent” and “stenting” are defined to include any of thewide variety of prostheses and scaffolds that are designed to beintraluminally introduced to a treatment site to apply a radiallyoutward force against the inner wall of the body lumen at that site. Theterms “prosthesis” and “prostheses” refer broadly to all stents andother scaffold-like structures that are intended for deployment withinbody lumens.

In one aspect of the invention, an apparatus is provided for deployingone or more prostheses into a target body lumen by isolating a targetregion of the lumen, introducing a fluidized prosthesis material intothe isolated region, shaping the fluidized material, and then allowingor causing the material to harden into a suitable prosthesis. Theapparatus comprises a flexible catheter having proximal and distal ends.The catheter may include a plurality of generally cylindrical shaftsthat are capable of sliding independently of one another, and one ormore lumens that may provide fluid communication between componentslocated at the proximal and distal ends of the catheter. The cathetermay also include a distal tip, preferably having a profile to reduce oreliminate the occurrence of trauma due to contact of the body lumen bythe tip.

A control member, such as a handle, may be provided to provide thecapability of manipulating the plurality of catheter shafts and othercatheter components. The control member may include one or more sliders,knobs, actuators, or other control members that are coupled to theplurality of catheter shafts and other catheter components to performthe manipulation functions. The control member may also provide ports orother connectivity mechanisms suitable for providing various fluid orother media to the lumens provided in the catheter. The fluids and othermedia may include inflation media for expansion members (e.g., balloons)located on the distal portion of the catheter, heating or cooling media,or fluidized prosthetic material for delivery to a treatment location.

A guidewire tube extends through at least a portion of the catheter andterminates at a distal exit port at the distal end of the catheter. Inone embodiment, for use in over-the-wire applications, the guidewiretube extends over the entire length of the catheter and has a proximalexit port at the proximal end of the catheter. In another embodiment,for use in rapid exchange applications, the guidewire tube extendsthrough the distal end of the catheter and has a proximal exit portcloser to the distal end of the catheter than to the proximal end, andpreferably about 20-35 cm from the distal end of the catheter. In thislatter embodiment, the proximal exit port may be cut into the sidewallof one or more of the catheter shafts to face laterally, oralternatively oriented so as to face generally in a proximal direction.One or both of the guidewire tube exit ports may be fluid sealed orfluid sealable so as to limit the introduction of blood or other fluidsthrough the guidewire tube. Usually the guidewire tube is fixed relativeto at least one of the catheter shafts and may be attached thereto.

The distal end of the catheter is provided with a mechanism for forminga prosthesis at a target location within the body lumen. The prosthesisforming mechanism typically comprises a proximal isolation member and adistal isolation member, each of which is selectively and independentlyexpandable. Each of the proximal and distal expandable isolation membersis fixed relative to at least one of the catheter shafts, therebyproviding the capability of changing the position of one of theexpandable isolation members with respect to the other. For example, inone embodiment, the proximal expandable isolation member is fixed to anouter shaft of the catheter, and the distal expandable isolation memberis fixed to an inner shaft of the catheter. The outer shaft is slidableproximally relative to the inner shaft to provide the capability ofmoving the proximal expandable isolation member proximally relative tothe distal expandable isolation member, thereby changing thelongitudinal distance between the two expandable isolation members.

The distal end of the catheter is also provided with an exit port of afluid delivery member that is suitable for delivering a fluid materialto be formed into a prosthesis. The fluid delivery member is typically apassage provided in the catheter. The fluid delivery member may comprisea lumen, an annular passage, or another type of passage extendingproximally from the exit port to a proximal port on the proximal end ofthe catheter or directly to a fluid source. The exit port of the fluiddelivery member typically opens into a space located between the distaland proximal expandable isolation members. In one embodiment, the exitport is a single port at the terminal end of a lumen serving as thefluid delivery member. In another embodiment, the exit port is anannular port at the terminal end of an annular passage serving as thefluid delivery member. In yet another embodiment, the exit port may beformed as one or more exit holes formed in an internal catheter shaft,an expandable balloon, or other catheter structure located between theproximal and distal expandable isolation members.

The distal end of the catheter may also be provided with a prosthesismolding member, such as a selectively expandable balloon. Typically, theprosthesis molding member will be fixed to an inner catheter shaft andwill be located between the proximal and distal expandable isolationmembers. In several embodiments, the prosthesis molding member may beformed integrally with one or both of the proximal and distal expandableisolation members. The length of the prosthesis molding member ispreferably dependent upon the distance that the outer catheter shaft iswithdrawn relative to the inner catheter shaft upon which the prosthesismolding member is fixed. The prosthesis forming member preferably has ashape and size that is adapted to form the prosthesis as and after thefluid material is delivered. For example, the prosthesis forming membermay have a cross-sectional profile having an hourglass, tapered,stepped, barrel-shaped, or other shape suitable for forming theprosthesis within a body lumen.

In several embodiments, the distal end of the catheter may also beprovided with a mechanism for curing the prosthesis material after itsdelivery to aid in the formation of the prosthesis. Typically, thecuring mechanism comprises an emitter for delivering energy, such asultraviolet (UV), infrared (IR), radio frequency (RF), microwave (MW),laser, or other suitable form of energy. The energy is typicallydirected radially from the emitter outward to encounter the prostheticmaterial to promote curing of the material.

In another aspect of the invention, a method of delivering a prosthesisin a target vessel of a patient comprises introducing a distal portionof a catheter through the patient's vasculature to the target vessel,isolating a void space between the distal end of the catheter and asurface of the target vessel, introducing a liquid prosthetic materialinto the void space, then forming the liquid prosthetic material into amolded shape to form a prosthesis.

The step of creating a void space at a target site within the vessel mayinclude inflating a proximal isolation balloon fixed to the outer shaft,inflating a distal isolation balloon fixed to the internal shaft, andinflating a molding balloon fixed to the internal shaft between theproximal and distal isolation balloons. The isolation balloons andmolding balloon cooperate with the internal surface of the vessel tocreate a tubular void space. The relative positions of the isolationballoons may be adjusted in order to adjust the length and size of thetubular void space, thereby providing the ability to form a prosthesisof a selected, adjustable length. A fluidized prosthesis material maythen be introduced into the void space, such as by injecting through adelivery lumen provided in the delivery catheter. The delivery lumen maybe provided with one or more exit ports located in the void space. Afterthe fluidized prosthesis material is introduced into the void space, itis allowed to harden or caused to harden, such as by exposing thematerial to a curing mechanism.

In another aspect of the invention, an apparatus is provided fordeploying one or more prostheses into a target body lumen by advancing adistal end of a delivery device to a body lumen treatment site, exposinga desired length of prosthetic material in pliable form, conforming thepliable prosthetic material to its deployment shape, and then allowingor causing the pliable prosthetic material to harden into a suitableprosthesis. The apparatus comprises a flexible catheter having proximaland distal ends. The catheter may include a plurality of generallycylindrical shafts that are capable of sliding independently of oneanother, and one or more lumens that may provide fluid communicationbetween components located at the proximal and distal ends of thecatheter. The catheter may also include a distal tip, preferably havinga profile to reduce or eliminate the occurrence of trauma due to contactof the body lumen by the tip.

A control member, such as a handle, may be provided to provide thecapability of manipulating the plurality of catheter shafts and othercatheter components. The control member may include one or more sliders,knobs, actuators, or other control members that are coupled to theplurality of catheter shafts and other catheter components to performthe manipulation functions. The control member may also provide ports orother connectivity mechanisms suitable for providing various fluid orother media to the lumens provided in the catheter. The fluids and othermedia may include inflation media for expansion members (e.g., balloons)located on the distal portion of the catheter, heating or cooling media,or fluidized prosthetic material for delivery to a treatment location.

A guidewire tube extends through at least a portion of the catheter andterminates at a distal exit port at the distal end of the catheter. Inone embodiment, for use in over-the-wire applications, the guidewiretube extends over the entire length of the catheter and has a proximalexit port at the proximal end of the catheter. In another embodiment,for use in rapid exchange applications, the guidewire tube extendsthrough the distal end of the catheter and has a proximal exit portcloser to the distal end of the catheter than to the proximal end, andpreferably about 20-35 cm from the distal end of the catheter. In thislatter embodiment, the proximal exit port may be cut into the sidewallof one or more of the catheter shafts to face laterally, oralternatively oriented so as to face generally in a proximal direction.One or both of the guidewire tube exit ports may be fluid sealed orfluid sealable so as to limit the introduction of blood or other fluidsthrough the guidewire tube. Usually the guidewire tube is fixed relativeto at least one of the catheter shafts and may be attached thereto.

The distal end of the catheter is provided with a mechanism for creatinga tubular prosthesis of a selectable length at a target site within thebody lumen. The mechanism includes an outer sheath that may be retractedto expose a selectable length of a pliable, flexible pre-stent member.As used herein, the term “pre-stent member” means a generally tubularbody that is flexible and pliable such that it may be expanded from afirst diameter small enough to be housed within the delivery catheter toa second diameter large enough to conform to the internal surface of atarget vessel or organ. The pre-stent member comprises a material thatis capable of transforming (or being transformed) from a first pliable,flexible state suitable for delivery by the catheter to a second morerigid state suitable for performing a scaffolding function within thetarget vessel or organ. The flexible pre-stent member then expands, oris expanded by the user, to conform to the interior of the lumen. Thepre-stent member then hardens, or is caused to harden, to form aresilient prosthesis with sufficient radial strength to provide ascaffold.

In one embodiment, the flexible pre-stent member comprises a tube-shapedlength of material that extends proximally from near the distal end ofthe catheter beneath the outer sheath. Preferably, a variable lengthexpandable member is provided, such as an inflatable balloon, which alsoextends proximally from near the distal end of the catheter beneath thepre-stent member. When the outer sheath is withdrawn, it exposes aselected length of the flexible pre-stent member and the underlyingexpandable member. The expandable member may then be expanded to causethe exposed length of flexible pre-stent member to conform to theinterior of the body lumen.

The length of the expandable member is preferably controlled by thedistance the outer sheath is retracted. For example, the outer sheathmay be a fiber-reinforced shaft that is capable of preventing orsubstantially inhibiting those portions of the expandable member thatare covered by the outer sheath from expanding when the remainder of theexpandable member is caused to expand. Alternatively, a separaterestraining member, such as another catheter shaft, may be provided toallow selective expansion of the expandable member.

A cutting device may be provided near the distal end of the outersheath, either formed as part of the distal end of the outer sheath oras a separate member. The cutting device may comprise a mechanicalcutter such as a cutting blade, a heating element, an electrode, anelectrolytic cutter, an ultrasonic cutter, a chemical cutter, or anyother form of cutting device suitable for creating a separation in theflexible pre-stent member. Preferably, the cutting device is alsocapable of sealing the cut portion of the prosthesis material when suchsealing is necessary or desired. A separate expandable isolation member,such as another inflatable balloon, may be provided near the distal endof the outer sheath but proximal to the cutting device.

In another embodiment, the pre-stent member may be provided as aninflatable member, such as a cylindrical tubular member having anannular fluid lumen, a coil-shaped tubular member in which the coil hasa fluid lumen, a tubular lattice having a fluid lumen, or other similarstructure. In this embodiment, the deployed pre-stent member may beexpanded by an inflation member such as the one described above, or itmay be expanded by inflating the lumen contained in the body of theflexible pre-stent member after it has been exposed by retracting theouter sheath, or a combination of both. The material used to inflate thepre-stent member may comprise fluidized prosthesis material, a hardeningagent, a filler, or some other material. In a particularly preferredform, the inflation medium may include a drug that is able to elutethrough porous walls of the prosthesis.

The inflatable pre-stent member may be free from attachment to thecatheter at its distal end, or it may be attached to an inner shaft, thedistal tip, or some other catheter component at its distal end. If thedistal end of the pre-stent member is free from attachment, it ispreferably sealed to facilitate inflation of the prosthesis. If thedistal end of the pre-stent member is attached to the catheter at itsdistal end, it may also be cut from the catheter by the cutting deviceby advancing the cutting device distally after the proximal portion ofthe pre-stent member is cut. Optionally, after cutting, the cuttingdevice will seal the ends of the pre-stent member.

In several of the foregoing embodiments, the distal end of the cathetermay also be provided with a mechanism for curing the pre-stent memberafter its delivery to aid in the formation of the prosthesis. Typically,the curing mechanism comprises an emitter for delivering energy, such asultraviolet (UV), infrared (IR), radio frequency (RF), microwave (MW),laser, or other suitable form of energy. The energy is typicallydirected radially from the emitter outward to encounter the pre-stentmember to promote curing of the material.

In another aspect of the invention, a method of delivering a prosthesisin a target vessel of a patient comprises inserting a guidewire throughthe patient's vasculature to the target vessel; slidably coupling adelivery catheter to the guidewire, the delivery catheter having anouter shaft, a flexible tubular pre-stent member of a prosthesismaterial, and a cutting device, the guidewire being slidably positionedthrough a guidewire tube; advancing the delivery catheter over theguidewire to the target vessel; retracting the outer shaft relative tothe tubular pre-stent member; expanding or causing to expand theflexible pre-stent member; and allowing or causing the flexiblepre-stent member material to harden.

The prostheses formed using the apparatus and methods described hereinare particularly suitable for use as stents, and particularly stents foruse in the coronary arteries. The stents may be formed of any of anumber of known materials suitable for use, including several knownpolymers, metals, ceramics, proteins, or other materials that may beused in fluid form at room temperature and/or body temperature and thatmay be cured or hardened and remain sufficiently resilient while incontact with blood or other bodily fluids. Examples of polymers that maybe used in the prostheses described herein are bioabsorbable orbiocompatible polymers such as poly(lactide) (PLA), poly(glycolic acid)(PGA), poly(lactide-co-glycolide) (PLGA), and other polyhydroxyacids,polyethylene glycol (PEG), poly(caprolactone), polycarbonates,polyamides, polyanhydrides, polyamino acids, polyortho esters,polyacetals, degradable polycyanoacrylates and degradable polyurethanes.Various hardenable materials including 2-part epoxies, polyurethanes andother materials suitable for use with the invention are described inU.S. Pat. No. 6,875,212, which is incorporated herein by reference.Various other hardenable materials including compounds of proteins andpolymers suitable for use with the invention are described in U.S. Pat.No. 6,371,975, which is incorporated herein by reference. Still otherhardenable materials including compounds having an electrophilic polymermaterial and a nucleophilic polymer material in a buffer materialsuitable for use with the invention are described in U.S. Pat. No.6,830,756, which is incorporated herein by reference. Examples ofnatural polymers and materials include proteins such as albumin,collagen, fibrin, fibrinogen, hydroxyapatite (HAp), and syntheticpolyamino acids, and polysaccharides such as alginate, heparin, andother naturally occurring biodegradable polymers of sugar units.Additional suitable materials are also described in, for example, U.S.Pat. Nos. 5,059,211, 5,085,629, 5,147,385, 5,213,580, 5,670,161,5,749,922, 5,947,977, 6,039,757, 6,607,553, and 6,623,519, each of whichis incorporated herein by reference. Composites comprising any of theabove materials combined with other biocompatible materials includingmetals, ceramics, carbon materials, and plastics may also be used toproduce the desired strength, flexibility, elution, and bioerosioncharacteristics. Further, any of these materials may be used incombination with scaffolds, braids, or other strengthening materials,including woven metals or polymers, textile fabrics, metal or carbonfibers, and the like. In addition, these materials may be mixed not onlywith active therapeutic agents as described elsewhere herein, but withmaterials to enhance visibility via fluoroscopy, ultrasound, or magneticresonance imaging. For example, fillers of radiopaque powders such asplatinum, tantalum, tungsten, iridium, or gold may be combined with thematerials above.

The finished prosthesis is preferably sufficiently resilient and/orradially rigid to perform the scaffolding function within the targetvessel. The degree of strength and flexibility required will varydepending, at least in part, on the vessel environment and the intendeduse. Typically, the prosthesis will be hardened, by which it is meantthat the material has sufficient structural strength to provide theoutward radial forces required to at least temporarily scaffold thevessel and maintain its patency. However, the hardened material willdesirably have flexibility to allow the prosthesis to assume curved andother non-linear shapes to conform to the natural shape of the vesseland the movement of the vessel (e.g., as the heart beats). Theprosthesis material may harden after the passage of seconds or minutes,or it may be cured using separate means, as discussed above andelsewhere herein. For example, the material may be hardened by adding ahardening agent in situ (similar to a 2-part epoxy). The material mayalternatively be cured by radiating it with energy such as UV or IRlight, ultrasound, or RF energy emitted by the delivery catheter itselfor by an external source (outside the vessel or outside the body). Thestent material could alternatively be cured by heating or cooling via aheating or cooling element on the catheter, or by delivering a warm orcool liquid such as saline through the catheter into the isolated spacewhere the stent is formed.

The prosthesis material may optionally be biodegradable so as to beeventually absorbed or expelled by the body. In many applications suchas coronary stenting, the stent need perform a scaffolding function foronly 30-60 days following placement to allow the drug to elute into thevessel, after which complete biodegradation of the stent is acceptable.

The prostheses described herein may also be combined or used inconjunction with other stent structures. For example, the prosthesesdescribed herein may be formed and delivered to a treatment locationalready having a metallic or other stent, or simultaneously with anothermetallic or other stent, in order to provide additional scaffolding, todeliver therapeutic materials contained on or in the prosthesis, orother functions. In several embodiments, a biodegradable material may beused to form a prosthesis that is used in conjunction with a metallic orother stent that has been previously deployed or that is deployedsimultaneously with the prosthesis. The prosthesis and the metallic orother stent may be deployed from separate delivery devices or,preferably, from a single delivery catheter. In several embodiments, themetallic or other stent and the prosthesis are formed from materialsthat biodegrade at different rates, while in other embodiments theprosthesis and the metallic or other stent are formed from materialsthat biodegrade at the same or substantially similar rates. The user isthereby able to select combinations of materials to obtain desiredresults.

In each of the embodiments described herein, the prosthesis material maybe combined with a drug or other therapeutic agent that inhibitsrestenosis, reduces thrombus formation or has other therapeutic effects.The drug or agent may be mixed with the prosthesis material andintroduced with it to form the prosthesis, or the drug may be introducedinto the isolated region separately from the prosthesis material, eithersimultaneously, before, or after introduction of the prosthesismaterial. For example, the prosthesis material and drug could beintroduced in an alternating fashion so that the prosthesis has asandwich structure with separate layers of drug and prosthesis material.Examples of drugs that may be included in the foregoing structuresinclude taxol, rapamycin, analogs of rapamycin such as Everolimus,Biolimus A9, or ABT 578, thrombolytics such as heparin, as well as VEGF,gene therapy agents, and a range of other agents known to those ofordinary skill in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a stent delivery catheter.

FIG. 2A is a side view, shown in partial cross-section, of an embodimentof a distal portion of a stent delivery catheter.

FIG. 2B is a side view, shown in partial cross-section, of anotherembodiment of a distal portion of a stent delivery catheter.

FIG. 2C is a side view, shown in partial cross-section, of the deviceshown in either of FIG. 2A or 2B.

FIG. 2D is a side view, shown in partial cross-section, of the deviceshown in either of FIG. 2A or 2B.

FIG. 2E is a side view, shown in partial cross-section, of anotherembodiment of a distal portion of a stent delivery catheter.

FIG. 2F is a side view, shown in partial cross-section, of the deviceshown in FIG. 2E.

FIG. 2G is a side view, shown in partial cross-section, of anotherembodiment of a distal portion of a stent delivery catheter.

FIG. 2H is a side view, shown in partial cross-section, of the deviceshown in FIG. 2G.

FIG. 2I is another side view, shown in partial cross-section, of thedevice shown in FIG. 2G.

FIG. 3A is a side view, shown in partial cross-section, of anotherembodiment of a distal portion of a stent delivery catheter.

FIG. 3B is a side view, shown in partial cross-section, of the deviceshown in FIG. 3A with the outer sheath retracted.

FIG. 3C is a side view, shown in partial cross-section, of the deviceshown in FIG. 3A, with the proximal isolation balloon expanded.

FIG. 3D is a side view, shown in partial cross-section, of the deviceshown in FIG. 3A, with the distal balloon expanded.

FIG. 3E is a side view, shown in partial cross-section, of the deviceshown in FIG. 3A, with the fluid stent material delivered.

FIG. 3F is a side view, shown in partial cross-section, of the deviceshown in FIG. 3A, being withdrawn from the treatment location.

FIG. 4A is a side view of another embodiment of a distal portion of astent delivery catheter.

FIG. 4B is a side view of the device shown in FIG. 4A illustratinginjection of fluid stent material.

FIG. 4C is a side view of the device shown in FIG. 4A illustratingmolding of the fluid stent material.

FIG. 4D is a side view of the device shown in FIG. 4A, being withdrawnfrom the treatment location.

FIG. 5A is a side view, shown in partial cross-section, of anotherembodiment of a distal portion of a stent delivery catheter.

FIG. 5B is a side view, shown in partial cross-section, of the deviceshown in FIG. 5A, with an illustration of exposure to a curingmechanism.

FIG. 5C is a side view, shown in partial cross-section, of the deviceshown in FIG. 5A, being withdrawn from the treatment location.

FIG. 6A is a side view, shown in partial cross-section, of anotherembodiment of a distal portion of a stent delivery catheter.

FIG. 6B is a side view, shown in partial cross-section, of the deviceshown in FIG. 6A, with an illustration of expansion of a pre-stentmember.

FIG. 6C is a side view, shown in partial cross-section, of the deviceshown in FIG. 6A, after shearing of a pre-stent member.

FIG. 7A is a side view, shown in partial cross-section, of anotherembodiment of a distal portion of a stent delivery catheter.

FIG. 7B is a side view, shown in partial cross-section, of the deviceshown in FIG. 7A, after shearing of a pre-stent member.

FIG. 8A is a side view of another embodiment of a distal portion of astent delivery catheter.

FIG. 8B is a side view of the device shown in FIG. 8A, illustratingexpansion of a pre-stent member.

FIG. 8C is a side view, shown in partial cross-section, of the deviceshown in FIG. 8A, illustrating shearing of a pre-stent member.

FIG. 8D is a side view, shown in partial cross-section, of the deviceshown in FIG. 8A, further illustrating shearing of a pre-stent member.

FIG. 8E is a side view of the device shown in FIG. 8A, after shearing ofa pre-stent member.

FIG. 9A illustrates a portion of a cylindrical pre-stent member.

FIG. 9B illustrates a portion of a coil-shaped pre-stent member.

FIG. 9C illustrates a portion of a lattice-shaped pre-stent member.

FIG. 10A is a side view, shown in partial cross-section, of anotherembodiment of a distal portion of a stent delivery catheter.

FIG. 10B is a side view, shown in partial cross-section, of the deviceshown in FIG. 10A, illustrating shearing of the proximal end of thepre-stent member.

FIG. 10C is a side view, shown in partial cross-section, of the deviceshown in FIG. 10A, illustrating shearing of the distal end of thepre-stent member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Xtent, Inc., assignee of the present application, is also the assigneeof U.S. patent application Ser. No. 10/306,813, filed Nov. 27, 2002,entitled “Apparatus and Methods for Delivery of Multiple DistributedStents” (“the '813 application”), and U.S. patent application Ser. No.10/637,713, filed Aug. 8, 2003, entitled “Apparatus and Methods forDeployment of Vascular Prostheses” (“the '713 application”). Each of theforegoing applications is hereby incorporated by reference in itsentirety.

A first embodiment of a prosthesis forming and deploying apparatus isillustrated in FIG. 1. A stent delivery catheter 20 includes a catheterbody 22 comprising an outer sheath 24 slidably disposed over an innershaft 26. A tapered nosecone 28 composed of a soft elastomeric materialto reduce trauma to the vessel during advancement of the device, isfixed to the distal end 29 of the catheter 20. A guidewire tube 30 isslidably positioned through a guidewire tube exit port 32 in the outersheath 24 at a proximal distance from the distal end 29 of the catheter.A guidewire 34 is positioned slidably through the guidewire tube 30, thedistal end 29 of the catheter, and the nosecone 28 and extends distallythereof.

A handle 40 is attached to a proximal end of the outer sheath 24 andincludes an actuator 42 slidably mounted thereto for purposes describedbelow. An adaptor 44 is mounted to the proximal end of the handle 40 andprovides a catheter port 46 through which the inner shaft 26 is slidablypositioned. A first fluid introduction port 48 is mounted to the side ofthe adaptor 44 through which a fluid may be delivered through thecatheter body to the distal portion of the catheter. A second fluidintroduction port 50 is also mounted to the side of the adaptor 44through which another fluid (or the same fluid) may be delivered to thedistal portion of the catheter. In several embodiments described herein,the first fluid introduction port 48 is used to deliver a fluidizedstent material (described more fully below) to the distal portion of thecatheter, and the second introduction port 50 is used to deliver aninflation medium to an expandable member (such as a balloon) located onthe distal portion of the catheter. An annular seal (not shown) in thecatheter port seals around the inner shaft 26 to prevent fluid fromleaking through the catheter port 46. Optionally, a clamp (also notshown) such as a threaded collar, can be mounted to the catheter port tolock the inner shaft relative to the handle.

The inner shaft 26 has a proximal end to which is mounted an inflationadaptor 52. The inflation adaptor 52 is configured to be fluidly coupledto an inflation device 54, which may be any commercially availableballoon inflation device such as those sold under the trade name“Indeflator™,” available from Advanced Cardiovascular Systems of SantaClara, Calif. (Similarly, such an inflation device 54 may also be usedto deliver an inflation medium through the second introduction port 52.)The inflation adaptor 52 may be placed in fluid communication with oneor more expandable members (such as balloons) located at or near thedistal end of the catheter via one or more inflation lumens to enableinflation of the one or more expandable members.

Those skilled in the art will recognize that the features on andfunctions performed by the handle 40 and its components may be modifiedor augmented in ways that are generally conventional in the art. Forexample, several embodiments of the delivery catheters described hereininclude multiple expandable members, such as inflation balloons, thathave inflation lumens in fluid communication with the handle 40. Severalembodiments of the delivery catheters described herein also includeother lumens in fluid communication with the handle 40 for delivery ofother fluid media, such as fluid stent material or heating or coolingmedia. Other embodiments include energy emitters in conductivecommunication with the handle 40. Persons of skill in the art willrecognize that additional ports, inflation devices, fluid sources,energy sources, and other features may be included on or in associationwith the handle 40 illustrated in FIG. 1.

Referring now to FIGS. 2A-2I, a distal portion 29 of a stent deliverycatheter 20 is shown in partial cross-section within the interior of ablood vessel 60 having a lesion 62. As shown in FIG. 2A, the outersheath 24 has been retracted to expose a portion of the distal end ofthe inner shaft 26 proximal to the nosecone 28. A proximal isolationballoon 70 is fixed to the outer sheath 24 near its distal end. Aninflation lumen (not shown) is provided in the outer sheath 24 extendingfrom the proximal isolation balloon 70 to the proximal end of the outersheath where it can be attached to a port and an inflation device toselectively expand or contract the proximal isolation balloon 70.Similarly, a distal isolation balloon 72 is fixed to the inner shaft 26near its distal end. Another inflation lumen (not shown) is provided inthe inner shaft 26 extending from the distal isolation balloon 72 to theproximal end of the inner shaft 26 where it can be attached to a portand an inflation device to selectively expand or contract the distalisolation balloon 72. Although each of the proximal and distal isolationballoons is shown in its expanded state, it will be understood that eachof the isolation balloons may be contracted in order to more easilyadvance or retract the outer sheath 24 or the catheter 20.

Prior to inflating the proximal isolation balloon 70, the outer sheath24 may be retracted over a range of distance relative to the inner shaft26 by actuation of the actuator 42 on the handle 40. For example, in thepreferred embodiment, the outer sheath 24 may be retracted over a rangeof distances from about 1 mm to about 100 mm. As shown more fully below,the amount of retraction of the outer sheath 24 relative to the innershaft 26 will determine the length of a prosthesis to be formed by thedelivery catheter 20. Thus, the adjustability of the distance that theouter sheath 24 may be retracted creates an ability by the user to formand deploy a stent having a desired length.

Once the outer sheath 24 has been retracted by a distance sufficient toform a stent of the desired length, the proximal isolation balloon 70and distal isolation balloon 72 may be expanded. Expansion of theisolation balloons creates a void space 80 within the blood vessel 60between the pair of isolation balloons. The void space 80 is defined, atleast initially, by the isolation balloons 70, 72, the internal vesselwall 61, and the inner shaft 26 of the delivery catheter.

Once the void space 80 is created, a fluidized stent material 82 may beintroduced into the void space 80. In the embodiment shown in FIG. 2A,the fluidized stent material 82 may be delivered into the void space 80through the lumen 25 formed in the annular space between the outersheath 24 and the inner shaft 26. The proximal end of the lumen 25 isconnected by a port (not shown) to a source of fluidized stent material.In the embodiment shown in FIG. 2B, the fluidized stent material 82 maybe delivered into the void space 80 through a plurality of ports 27 anda fluid lumen located in the inner shaft 26. The proximal end of theinner shaft lumen is connected by a port (also not shown) to a source offluidized stent material. The stent material is introduced in a fluidstate in order to fill the void space 80 created by the distal end 29 ofthe delivery catheter and the internal surface of the blood vessel 60.

As shown in FIG. 2C, in one embodiment, as the fluidized stent material82 is delivered, it takes the shape of the void space 80, which isgenerally a cylindrical shape. Once the desired shape has been obtained,the fluid stent material 82 is allowed to harden, or caused to harden bya curing mechanism, as described more fully below.

FIG. 2D illustrates another embodiment, in which a molding balloon 74 isprovided on the inner shaft 26. The molding balloon 74 is connected byan inflation lumen to an inflation source at the proximal end of thecatheter. The molding balloon 74 is inflated after the fluid stentmaterial 82 has been introduced into the void space 80. Inflating themolding balloon 74 causes the fluid stent material 82 to conform to theshape of the void space 80 at it is modified by the molding balloon 74.The molding balloon 74 may have a generally cylindrical profile, asillustrated in FIG. 2D, or it may have any other shape to achieve adesired shape for the molded stent, such as an hourglass shape, atapered shape, a stepped shape, a barrel-shape, or others. The shape ofthe molding balloon 74 is imparted to the internal surface of the stent,as shown in FIG. 2D. The volume of stent material introduced and theinflation pressure of the molding balloon 74 may be selected so as tocreate a stent of desired size and shape within the vessel.

FIGS. 2E-F illustrate yet another embodiment, in which the moldingballoon is formed integrally with the distal isolation balloon. In thisembodiment, a single combination balloon 76 is used to both isolate thevoid space 80 and to shape or mold the fluid stent material 82 into astent 84. The balloon 76 includes a distal portion 77 having a diametersuitable for sealing against the internal surface of the blood vessel,and a molding portion 78 having a diameter and shape suitable formolding and shaping the fluid stent material 82 against the internalwall 61 of the body lumen 60. The distal portion 77 of the balloon maybe inflated initially with a secondary sheath 79 surrounding the moldingportion 78 to isolate the void space 80 between the distal portion 77and the proximal isolation balloon 70. Then, after the void space 80 hasbeen filled with the liquid stent material 82, the molding portion 78 ofthe balloon may be expanded by retracting the secondary sheath 79surrounding the molding portion 78 of the balloon 76 a sufficientdistance to allow the molding portion 78 to expand in the void space 80.(See FIG. 2E). Once the secondary sheath 79 has been retracted such thatits distal end is at the same position as the distal end of the outersheath 24, the molding portion 78 of the balloon occupies a portion ofthe void space 80 extending from the distal portion 77 of the balloon tothe proximal isolation balloon 70, thereby forming the stent materialinto a stent of suitable wall thickness and shape.

FIGS. 2G-I illustrate another embodiment of a distal portion of a stentdelivery catheter in which a metal or polymer stent 86 is delivered tothe treatment location prior to formation and delivery of a fluidizedstent material at the same treatment location. As shown in FIG. 2G, thedelivery catheter includes a proximal isolation balloon 70 fixed to theouter sheath 24 and a distal isolation balloon 72 fixed to the innershaft 26. A nosecone 28 is fixed to the distal end of the inner shaft26, and a guidewire 34 extends through a guidewire lumen located in thecatheter.

The metal or polymer stent 86 is carried by the catheter in the annularlumen 25 between the outer sheath 24 and the inner shaft 26. When theouter sheath 24 is withdrawn, a selectable length of the metal orpolymer stent 86 is exposed. The stent 86 may have any of a variety ofcommon constructions, including helical structures, counterwound helicalstructures, expandable diamond structures, serpentine structures, or thelike. Preferably, the stent 86 is formed in discrete segments and isdelivered generally in a manner such as those taught in theaforementioned '813 and '713 applications, in order to provide theability to deploy a stent 86 having a selectable length.

The stent 86 may be self-expanding, or it may be expanded by use of anexpansion balloon 88 carried on the inner shaft 26. The expansionballoon 88 may be expanded, as shown in FIG. 2H, to expand the stent 86sufficiently to engage the inner wall of the lumen, after which theballoon 88 is contracted, as shown in FIG. 2I. Once the balloon iscontracted, a fluidized stent material 82 is injected through theannular lumen 25 into the void space to form a prosthesis. The fluidizedstent material 82 is allowed or cause to cure or harden in the mannerdescribed elsewhere herein. The balloon 88 may be expanded during orafter delivery of the fluidized stent material 82 in order to shape thefluidized material, similar to the manner described above in relation toFIG. 2D. Alternatively, the balloon 88 may not be used, and theprosthesis will be formed by the size of the inner shaft 26 to which isattached the uninflated balloon 88.

One or both of the stent 86 and the prosthesis formed from the fluidizedmaterial may be formed of biodegradable materials, such as thosedescribed previously herein. The materials making up the stent 86 andthe prosthesis may biodegrade at the same or similar rates, or they maybiodegrade at substantially different rates, depending upon theapplication and the desired treatment. In addition, one or both of thestent 86 and the prosthesis may carry a drug or other therapeuticmaterial, either in a coating, or embedded or mixed in the material, orotherwise associated with the stent 86 or prosthesis.

FIGS. 3A-F illustrate another alternative embodiment of a distal portion29 of the prosthesis forming and deploying apparatus. In thisalternative embodiment, the fluid stent material 82 is delivered to thevoid space 80 by way of an inflatable balloon 176 having a plurality ofholes 175, pores, or other ports, through which the fluid stent materialpasses. The proximal isolation balloon 70 is fixed to the outer sheath24 near its distal end. An inflation lumen (not shown) is provided inthe outer sheath 24 extending from the proximal isolation balloon 70 tothe proximal end of the outer sheath 24 where it can be attached to aport and an inflation device to selectively expand or contract theproximal isolation balloon. A tapered nosecone 28 composed of a softelastomeric material to reduce trauma to the vessel during advancementof the device, is fixed to the distal end 29 of the catheter 20.

Once the distal end 29 of the catheter is properly located at the siteof a lesion 62 on the internal surface 61 of the blood vessel 60, theouter sheath 24 is retracted to expose an uninflated distal balloon 176affixed to the distal end of the catheter. The uninflated distal balloon176 typically has a length of about 20 mm to about 200 mm, morepreferably about 40 mm to about 100 mm, extending proximally from nearthe distal end of the catheter and is generally covered by the outersheath 24. When the outer sheath 24 is positioned over the distalballoon 176, it prevents the distal balloon from inflating. Only whenthe outer sheath 24 is retracted is the distal balloon 176 able to beexpanded. Thus, the length of the expandable portion of the distalballoon 176 is able to be controlled by the amount that the outer sheath24 is retracted.

Turning to FIG. 3B, the outer sheath 24 has been retracted a sufficientdistance to enable the distal balloon 176, once inflated, to extend overthe length of the lesion 62. The proximal isolation balloon 70 may thenbe expanded (see FIG. 3C) to seal off blood flow in the vessel. Thedistal balloon 176 is then inflated, preferably by injecting fluid stentmaterial 82 into the balloon to cause the balloon to expand. Theexpanded distal balloon 176, as shown for example in FIG. 3D, preferablyhas a distal isolation portion 177 having a diameter suitable forengaging the inner surface of the vessel in order to seal off the voidspace 80 created in the blood vessel from distally of the lesion. Theproximal portion 178 of the distal balloon has a relatively smallerdiameter, thereby creating a void space 80 in the vessel between theinflated balloons and the vessel wall 61. The proximal portion 178 maybe cylindrical or may have various other shapes to create a stent ofdesired shape.

A plurality of holes 175, pores, or another form of ports, are formed inthe proximal portion 178 of the distal balloon, allowing the fluid stentmaterial 82 to pass through the balloon into the void space 80. Thus,the action of inflating the balloon also causes the fluid stent material82 to be delivered into the void space 80 created by the engagement ofthe balloons with the internal surface 61 of the blood vessel 60. Oncethe fluid stent material 82 has been delivered, it is allowed to hardenor caused to harden to form a stent 84 at the lesion site within theblood vessel. See FIG. 3E. Once the stent 84 is formed and cured, theproximal isolation balloon 70 and distal balloon 176 are contracted, andthe catheter 20 may be withdrawn. See FIG. 3F.

FIGS. 4A-D illustrate yet another alternative embodiment of a distalportion 29 of the prosthesis forming and deploying apparatus. In thisalternative embodiment, the proximal isolation balloon 70 is fixed tothe outer sheath 24 near its distal end. An inflation lumen (not shown)is provided in the outer sheath 24 extending from the proximal isolationballoon to the proximal end of the outer sheath 24 where it can beattached to a port and an inflation device to selectively expand orcontract the proximal isolation balloon. A tapered nosecone 28 composedof a soft elastomeric material to reduce trauma to the vessel duringadvancement of the device, is fixed to the distal end 29 of the catheter20.

Once the distal end of the catheter is properly located at the site of alesion 62 on the internal surface 61 of the blood vessel 60, the outersheath 24 is retracted to expose an uninflated distal balloon 76extending from near the distal end of the catheter. The uninflateddistal balloon 76 typically has a length of about 60 mm extendingproximally from near the distal end of the catheter 20 and is generallycovered by the outer sheath 24. When the outer sheath 24 is positionedover the distal balloon 76, it prevents the distal balloon 76 frominflating. Only when the outer sheath 24 is retracted is the distalballoon 76 able to be expanded. Thus, the length of the expandableportion of the distal balloon 76 is able to be controlled by the amountthat the outer sheath 24 is retracted.

As shown in FIGS. 4A-B, the outer sheath 24 has been retracted asufficient distance to enable the exposed portion of the distal balloon76, once inflated, to extend over the length of the lesion 62. Theproximal isolation balloon 70 may then be expanded (see FIGS. 4A-C) toseal off blood flow in the vessel 60. The distal balloon 76 is theninflated. The expanded distal balloon, as shown for example in FIG. 4A,preferably has a distal isolation portion 77 having a diameterconfigured to engage the inner wall of the vessel to seal off the voidspace 80 created in the blood vessel from distally of the lesion. Theproximal portion 78 of the distal balloon has a relatively smallerdiameter, thereby creating a void space 80 in the vessel between theinflated balloons and the vessel wall 61.

An annular stent material delivery passage 90 is provided between theouter sheath 24 and the distal balloon 76. Fluid stent material 82 maybe injected into the void space 80 between the distal balloon 76 and theinternal surface 61 of the blood vessel by way of the annular stentmaterial delivery passage 90. See FIG. 4B. Once the fluid stent material82 has been delivered, it is allowed to harden or caused to harden toform a stent 84 at the lesion site within the blood vessel. See FIG. 4C.Once the stent 84 is formed and cured, the proximal isolation balloon 70and distal balloon 76 are contracted, and the catheter may be withdrawn.See FIG. 4D.

FIGS. 5A-C illustrate another alternative embodiment of a distal portion29 of the prosthesis forming and deploying apparatus that employs acuring mechanism. In this alternative embodiment, the distal portion 29of the catheter is generally similar to the structure described above inrelation to FIGS. 4A-D, including a proximal balloon 70 attached to theouter sheath 24, a distal balloon 76 extending from near the distal endof the catheter beneath the outer sheath 24, and a tapered nosecone 28attached to the distal end of the catheter. The distal balloon 76 isprovided with a large diameter distal portion 77 for isolating the voidspace 80, and a smaller diameter molding portion 78 extending betweenthe distal portion 77 and the proximal isolation balloon 70.

The distal balloon 76 is mounted to an internal shaft 26 near the distalend of the catheter. The internal shaft 26 is provided with a pluralityof emitters 100 that are connected to an energy source (not shown) atthe proximal end of the catheter 20. The energy source may be a sourceof ultraviolet, radio frequency, microwave, laser, or any other energysuitable for curing a liquid stent material 82. For example, the stentmaterial may be of a type that more readily cures when exposed to aparticular source of energy, or it may include an appropriate curinginitiator that is susceptible to a particular source of energy, in whichcase the energy type and source is selected to be paired with theparticular stent material being used. Several examples of materials,energy types, and combinations thereof are described, for example, inU.S. Pat. No. 6,039,757, which is incorporated herein by reference.Alternatively, the stent material may comprise, may include, or may becoated with a radiation-absorbing material that is expandable followingexposure to radiation, as described in U.S. Pat. No. 6,607,553, which isincorporated herein by reference. The energy emitted will be capable ofpassing through the wall of the balloon 76 without damaging, deformingor weakening such wall material. Alternatively, the stent material maybe infused or mixed with a curing material that facilitates curing ofthe stent material when exposed to the particular energy source. Severalcombinations of energy and material suitable for these purposes arepossible, as will be readily understood by a person of skill in the art.

As shown in FIG. 5B, the emitters 100 emit the energy “E” radiallyoutward from their locations on the internal shaft 26 to impinge on thefluid stent material 82. Preferably, the material used to form thedistal balloon 76 is of a type that is permeable by the type of energyemitted from the emitters 100 on the internal shaft 26, such that theenergy is transmitted through the distal balloon 76 into the stentmaterial 82. After a sufficient amount of energy is emitted to cause thestent material 82 to cure (or to hasten curing), the energy emission isstopped. After the stent material 82 has hardened, the distal balloon 76and proximal isolation balloon 70 may be contracted, and the catheter 20removed from the treatment site (see FIG. 5C). It will be understoodthat emitters like those shown in FIGS. 5A-C may be used with any of theother embodiments described herein for curing the stent materials usedin such embodiments.

For each of the embodiments described above in relation to FIGS. 2A-F,3A-F, 4A-D, and 5A-C, the stent material is preferably any of severalknown materials suitable for use. Examples of suitable materials includeseveral known polymers, metals, ceramics, proteins, or other materialsthat may be used in fluid form at room temperature and/or bodytemperature and that may be cured or hardened and remain sufficientlyresilient while in contact with blood or other bodily fluids. Examplesof polymers that may be used in the prostheses described herein arebioabsorbable or biocompatible polymers such as poly(lactide) (PLA),poly(glycolic acid) (PGA), poly(lactide-co-glycolide) (PLGA), and otherpolyhydroxyacids, polyethylene glycol (PEG), poly(caprolactone),polycarbonates, polyamides, polyanhydrides, polyamino acids, polyorthoesters, polyacetals, degradable polycyanoacrylates and degradablepolyurethanes. Various hardenable materials including 2-part epoxies,polyurethanes and other materials suitable for use with the inventionare described in U.S. Pat. No. 6,875,212, which is incorporated hereinby reference. Various other hardenable materials including compounds ofproteins and polymers suitable for use with the invention are describedin U.S. Pat. No. 6,371,975, which is incorporated herein by reference.Still other hardenable materials including compounds having anelectrophilic polymer material and a nucleophilic polymer material in abuffer material suitable for use with the invention are described inU.S. Pat. No. 6,830,756, which is incorporated herein by reference.Examples of natural polymers and materials include proteins such asalbumin, collagen, fibrin, fibrinogen, hydroxyapatite (HAp), andsynthetic polyamino acids, and polysaccharides such as alginate,heparin, and other naturally occurring biodegradable polymers of sugarunits. Additional suitable materials are also described in, for example,U.S. Pat. Nos. 5,059,211, 5,085,629, 5,147,385, 5,213,580, 5,670,161,5,749,922, 5,947,977, 6,039,757, 6,607,553, and 6,623,519, each of whichis incorporated herein by reference. Composites comprising any of theabove materials combined with other biocompatible materials includingmetals, ceramics, carbon materials, and plastics may also be used toproduce the desired strength, flexibility, elution, and bioerosioncharacteristics. Further, any of these materials may be used incombination with scaffolds, braids, or other strengthening materials,including woven metals or polymers, textile fabrics, metal or carbonfibers, and the like. In addition, these materials may be mixed not onlywith active therapeutic agents as described elsewhere herein, but withmaterials to enhance visibility via fluoroscopy, ultrasound, or magneticresonance imaging. For example, fillers of radiopaque powders such asplatinum, tantalum, tungsten, iridium, or gold may be combined with thematerials above.

Each of the delivery catheter embodiments described above in relation toFIGS. 2A-F, 3A-F, 4A-D, and 5A-C, is capable of performing multiple insitu prosthesis formations and deliveries during a single interventionalprocedure, i.e., without fully withdrawing the catheter from thepatient's vasculature. This is done by performing the proceduresdescribed above in relation to those Figures, then relocating the distalportion 29 of the delivery catheter to another treatment location,within the same vessel or another vessel, and performing the formationand delivery procedure again at the second treatment location. This maybe repeated to form multiple prostheses of various lengths during asingle procedure.

Turning to FIGS. 6A-C, the distal portion 29 of an alternative stentforming and deployment apparatus and method are described. Thisalternative apparatus and method include use of a formable tubularpre-stent member that is able to be formed at selected lengths anddeployed at a treatment site, for example, within a blood vessel. Theapparatus includes an outer sheath 24 disposed over a tubular pre-stentmember 110 and an internal expandable member 120 (e.g., balloon). Theexpandable member 120 is attached to an internal shaft 26. A taperednosecone 28 composed of a soft elastomeric material to reduce trauma tothe vessel during advancement of the device, is fixed to the distal end29 of the device 20. An optional proximal isolation balloon 70 may beincluded on the external surface of the outer sheath 24 near the distalend of the outer sheath.

The outer sheath 24 includes a cutting mechanism 130 at its distal end,preferably on the internal surface of the outer sheath 24. The cuttingmechanism 130 may comprise a mechanical cutter such as a cutting blade,a heating element, an electrode, an electrolytic cutter, an ultrasoniccutter, a chemical cutter, or some other mechanism suitable forshearing, cutting, melting, or separating portions of the tubularpre-stent member 110. The cutting mechanism may be selectively actuatedby a control member on the proximal handle 40, or may operate passivelywhen contacted by the pre-stent member 110 during expansion. In the caseof an electrode, electrolytic, ultrasonic, or heating element, theelement or electrode is conductively connected to an energy sourceassociated with the proximal handle 40 in a conventional manner.

The outer sheath 24 is preferably formed of a conventional cathetertubing having sufficient strength and flexibility to navigate thepatient's vasculature, and also to restrict inflation of the portion ofthe expandable member 120 covered by the outer shaft 24. Examples ofsuitable materials include fiber reinforced polymers, particularlypolyurethane. The expandable member 120 is preferably a conventionalinflation balloon coupled by an inflation lumen to a source of inflationmedia associated with the proximal handle 40.

The tubular pre-stent member 110 may comprise any suitable material thatis soft, flexible, and pliable in a first state for delivery anddeployment, but subject to transformation into a rigid, relativelystronger second state to perform a scaffolding function at a treatmentsite in, for example, a blood vessel 60. Suitable materials includethose described above in relation to the fluid stent materials used inthe devices illustrated in FIGS. 2A-F, 3A-F, 4A-D, and 5A-C. Thetransformation is preferably made by curing or hardening the pre-stentmember 110 into a final deployed stent as described above in connectionwith other embodiments.

Turning to FIG. 6A, the catheter 20 is delivered to a location withinthe blood vessel 60 having a lesion 62 or other defect requiringtreatment. The distal portion 29 of the catheter is advancedsufficiently that the distal tip 28 is distal of the treatment site. Theouter sheath 24 is then retracted to expose the pre-stent member 110.The longitudinal distance that the outer sheath 24 is retracteddetermines the length of the pre-stent member 110 that ultimately willbe deployed, thus allowing the operator to select the length of thestent to match the length of the lesion being treated.

Once the outer sheath 24 is retracted, the proximal isolation balloon70, if present, may be expanded to isolate the treatment site from bloodflow. (See FIG. 6B). The expandable member 120 is then expanded, causingthe pre-stent member 110 to expand with the expandable member 120 and toconform with the internal surface 61 of the blood vessel at thetreatment site. The expandable member 120 is only allowed to expand inthe region that has been uncovered by the outer sheath 24, therebyexpanding the pre-stent member 110 over the length of the treatmentlocation. The pre-stent member 110 is then cut using the cuttingmechanism 130, thereby creating a free tubular pre-stent member 110fully expanded at the treatment location.

Once the pre-stent member 110 is expanded and cut, the expandable member120 is maintained in its expanded state a sufficient amount of time toallow the pre-stent member 110 to cure or harden. (See FIG. 6C). Curingor hardening may result from passage of a sufficient amount of time toallow the material to harden by itself, or curing may be facilitated bya curing mechanism. For example, the pre-stent member material may be ofa type that is caused to transform into a rigid, resilient material dueto the stress incurred during the balloon expansion step. The pre-stentmember may also further harden after sufficient time has passed afterthe expansion step. Curing may be further facilitated by exposure to aheating or cooling medium delivered into the expandable member 120.Alternatively, an energy source may be used to transmit ultraviolet,radio frequency, microwave, laser, or other energy to the flexiblepre-stent member to cause it to cure after deployment. For example, oneof the curing mechanisms described above in relation to FIGS. 5A-C maybe utilized to cure the pre-stent member 110 after deployment. In eithercase, the pre-stent member 110 is allowed or caused to cure such thatthe resulting stent 84 has sufficient radial strength and resilience toperform the desired stent scaffolding function.

After the pre-stent member 110 has been allowed or caused to harden, theexpandable member 120 may be contracted and retracted inside the outersheath 24. The catheter 20 may then be relocated to another treatmentsite within the target vessel or another vessel and the procedurerepeated for deployment of another stent, or the catheter may becompletely withdrawn.

Turning to FIGS. 7A-B, the distal portion 29 of another alternativestent forming and deployment apparatus and its method of use areillustrated. This alternative apparatus and method include use of aninflatable tubular pre-stent member 110 that is able to be formed atselected lengths and deployed at a treatment site, for example, within ablood vessel. The apparatus includes an outer sheath 24 disposed over aninflatable tubular pre-stent member 110. An optional internal expandablemember 120 (e.g., a balloon) may also be included in some embodiments.When it is present, the expandable member 120 is attached to an internalshaft 26. A tapered nosecone 28 composed of a soft elastomeric materialto reduce trauma to the vessel during advancement of the device, isfixed to the distal end 29 of the device 20. An optional proximalisolation balloon (not shown) may be included on the external surface ofthe outer sheath 24 near the distal end of the outer sheath.

The outer sheath 24 includes a cutting mechanism 130 at its distal end,preferably on the internal surface of the outer sheath. The cuttingmechanism 130 may comprise a mechanical cutter such as a cutting blade,a heating element, an electrode, an electrolytic cutter, an ultrasoniccutter, a chemical cutter, or some other mechanism suitable for shearingor separating portions of the tubular pre-stent member 110. The cuttingmechanism may be actuated by a control member on the proximal handle 40,or may operate passively when contacted by the pre-stent member 110 uponexpansion thereof. In the case of an electrode, electrolytic,ultrasonic, or heating element, the element or electrode is conductivelyconnected to an energy source associated with the proximal handle 40 ina conventional manner.

The outer sheath 24 is preferably formed of a conventional cathetertubing having sufficient strength and flexibility to navigate thepatient's vasculature, and also to restrict inflation of the portion ofthe expandable member 120 covered by the outer sheath 24. Examples ofsuitable materials include fiber reinforced polymers, particularlypolyurethane. The expandable member 120, when present, is preferably aconventional inflation balloon coupled by an inflation lumen to a sourceof inflation media associated with the proximal handle 40.

The tubular pre-stent member 110 is a generally tubular structure havingan internal wall 112, an external wall 114, an end wall 116, and anannular lumen 118 between the internal and external walls. The lumen 118is in fluid communication with a fluid delivery lumen in the shaft ofthe device which connects to a source of filling material 140 associatedwith the proximal handle 40. In some embodiments, the walls of thepre-stent member 110 are formed of a material having resiliencesufficient to cause the pre-stent member to expand radially outward whenthe outer sheath 24 is retracted. Preferably, the internal, external,and end walls of the pre-stent member are formed of a polymer material,a metal or metal alloy, or a blend of two or more of these materials.Examples of suitable materials include those fluid stent materialsdescribed above in relation to the delivery catheters illustrated inFIGS. 2A-F, 3A-F, 4A-D, and 5A-C.

Turning to FIG. 7A, the catheter 20 is delivered to a location withinthe blood vessel 60 having a lesion 62 or other defect requiringtreatment. The distal portion 29 of the catheter is advancedsufficiently that the distal tip 28 is distal of the treatment site. Theouter sheath 24 is then retracted to expose the inflatable pre-stentmember 110. The longitudinal distance that the outer sheath 24 isretracted determines the length of the pre-stent member 110 thatultimately will be deployed.

Once the outer sheath 24 is retracted, a fluid or filler material 140 isdelivered to the annular lumen 118 formed in the pre-stent member 110,thereby filling the annular lumen 118. The fluid or filler material 140may be any suitable material that provides desired physical propertiesto the stent. Preferably, the fluid or filler material 140 is a polymeror foam that is subject to hardening or curing once delivered into theannular lumen 118.

In one embodiment, injection of the fluid or filler material 140 causesthe pre-stent member 110 to expand to conform with the internal wall 61of the blood vessel 60 at the treatment location. In alternativeembodiments, the pre-stent member 110 may partially or fully self-expandto conform with the internal wall of the blood vessel prior to injectingthe fluid or filler material 140. In those embodiments in which thepre-stent member 110 is not self-expanding, or when additional expansionis desired, the pre-stent member 110 may be expanded or further expandedby an expandable member 120 provided on the internal shaft 26.

After the fluid or filler material 140 is delivered to the annular lumen118, the pre-stent member 110 is cut using the cutting mechanism 130 onthe outer sheath 24, thereby creating a free tubular pre-stent member110 fully expanded within the blood vessel 60. The cutting step may beperformed after the fluid or filler material 140 has hardened or curedsufficiently to prevent leakage from the cut portion of the pre-stentmember 110. Alternatively, the cutting member 130 may optionally sealthe pre-stent member, such as by cauterization (melting the stentmaterial) or mechanically sealing, to prevent the fluid or fillermaterial from leaking from the proximal end of the pre-stent member 110.

Once the pre-stent member 110 is expanded and cut, if the expandablemember 120 has been used, the expandable member 120 is maintained in itsexpanded state a sufficient amount of time to allow the pre-stent member110 to cure or harden. (See FIG. 7B). Curing or hardening may resultfrom passage of a sufficient amount of time to allow the fluid or fillermaterial 140 and the pre-stent member walls to harden by itself, orcuring may be facilitated by a curing mechanism. For example, thepre-stent member material may be of a type that is caused to transforminto a rigid, resilient material due to the stress incurred during theballoon expansion step. In such a case, the pre-stent member 110 willharden after sufficient time has passed after the expansion step. Curingmay be further facilitated by exposure to a heating or cooling mediumdelivered into the expanded balloon. Alternatively, an energy source maybe used to transmit ultraviolet, radio frequency, microwave, laser, orother energy to the flexible pre-stent member to cause it to cure afterdeployment. For example, one of the curing mechanisms described above inrelation to FIGS. 5A-C may be utilized to cure the pre-stent member 110after deployment. In either case, the pre-stent member 110 is allowed orcaused to cure such that the resulting stent 84 has sufficient radialstrength and resilience to perform the desired stent scaffoldingfunction.

After the pre-stent member has been allowed or caused to harden, theexpandable member 120 may be contracted and retracted inside the outersheath 24. The catheter 20 may then be relocated to another treatmentlocation and the procedure repeated for deployment of another stent, orthe catheter may be completely withdrawn.

FIGS. 8A-E illustrate the distal portion of another alternative stentforming and deployment apparatus and method. This alternative apparatusand method include use of another form of inflatable tubular pre-stentmember that is able to be formed at selected lengths and deployed at atreatment site, for example, within a blood vessel. The apparatusincludes an outer sheath 24 and a middle shaft 150 disposed over aninflatable tubular pre-stent member 110. An optional internal expandablemember 120 (e.g., a balloon) may also be included in some embodiments.When it is present, the expandable member 120 is attached to an internalshaft 26. A tapered nosecone 28 composed of a soft elastomeric materialto reduce trauma to the vessel during advancement of the device, isfixed to the distal end 29 of the device 20. An optional proximalisolation balloon (not shown) may be included on the external surface ofthe outer sheath 24 near the distal end of the outer sheath.

In the embodiment shown in FIGS. 8A-E, a cutting mechanism 130 islocated at the distal end of the middle shaft 150. (See FIGS. 8C-D). Thecutting mechanism 130 may comprise a mechanical cutter such as a cuttingblade, a heating element, an electrode, an electrolytic cutter, anultrasonic cutter, a chemical cutter, or some other mechanism suitablefor shearing or separating portions of the tubular pre-stent member 110.The cutting mechanism may be actuated by a control member on theproximal handle 40, or may operate passively as in other embodiments. Inthe case of an electrode, electrolytic, ultrasonic, or heating element,the element or electrode is conductively connected to an energy sourceassociated with the proximal handle 40 in a conventional manner.

The outer sheath 24 and middle shaft 150 are preferably formed ofconventional catheter tubing having sufficient strength and flexibilityto navigate the patient's vasculature, and also to restrict inflation ofthe expandable member. Examples of suitable materials include fiberreinforced polymers, particularly polyurethane. The expandable member120, when present, is preferably a conventional inflation ballooncoupled by an inflation lumen to a source of inflation media associatedwith the proximal handle 40.

The tubular pre-stent member 110 is a generally tubular structurecomprising a lattice 160 of interconnected tubes 162 each having lumens163 therein. In the embodiment shown in FIGS. 8A-E, the lattice 160 isin the form of a plurality of diamond shapes in which the interconnectedtubes 162 form a geometric matrix defining empty or void spaces 164having a diamond shape. Other variations of this lattice shape arepossible, such as lattices defining circular, triangular, square,pentagonal, wave-shaped, zig-zag, and other repeating patterns, orcombinations of such patterns. Still further variations may includeirregular void spaces. Each of these variations, or combinationsthereof, may be employed, as will be readily understood by persons ofskill in the art. The interconnected tubes 162 are, in turn, in fluidcommunication with a source of fluid filling material associated withthe proximal handle 40. In some embodiments, the interconnected tubes162 of the pre-stent member 110 are formed of a material havingresilience sufficient to cause the pre-stent member to expand radiallyoutward when the outer sheath 24 is retracted. Preferably, the tubes 162of the pre-stent member are formed of a polymer material, a metal ormetal alloy, or a blend of two or more of these materials. Examples ofsuitable materials include the fluid stent materials described above inrelation to the delivery catheters illustrated in FIGS. 2A-F, 3A-F,4A-D, and 5A-C.

Turning to FIG. 8A, the catheter 20 is delivered to a location withinthe blood vessel 60 having a lesion or other defect requiring treatment.The distal portion 29 of the catheter is advanced sufficiently that thedistal tip is distal of the treatment site. The outer sheath 24 is thenretracted to expose the inflatable pre-stent member 110. Thelongitudinal distance that the outer sheath 24 is retracted determinesthe length of the pre-stent member 110 that ultimately will be deployed.

Once the outer sheath 24 is retracted, a fluid or filler material 140 isdelivered to the lumens 163 formed in the body of the pre-stent member,thereby filling the lumens 163. The fluid or filler material 140 may beany suitable material that provides desired physical properties to thestent. Preferably, the fluid or filler material 140 is a polymer or foamthat is subject to hardening or curing once delivered into the annularlumen.

In one embodiment, injection of the fluid or filler material causes thepre-stent member 110 to expand to conform with the internal wall 61 ofthe blood vessel 60 at the treatment location. In alternativeembodiments, the pre-stent member 110 may partially or fully self-expandto conform with the internal wall 61 of the blood vessel 60 prior toinjecting the fluid or filler material 140. In those embodiments inwhich the pre-stent member 110 is not self-expanding, or when additionalexpansion is desired, the pre-stent member may be expanded or furtherexpanded by an expandable member 120 provided on the internal shaft 26.

After the fluid or filler material 140 is delivered to the pre-stentlumens 163, the pre-stent member 110 is cut using the cutting mechanism130 on the middle shaft 150, thereby creating a free tubular pre-stentmember 110 fully expanded within the blood vessel 60. The cutting stepmay be performed by advancing the middle shaft 150 relative to the outersheath 24 and the pre-stent member 110, thereby causing the cuttingmechanism 130 to engage and cut the pre-stent member 110 at the contactpoint with the cutting mechanism 130. The cutting step may be performedafter the fluid or filler material 140 has hardened or curedsufficiently to prevent leakage from the cut portion of the pre-stentmember. Alternatively, the cutting member 130 may optionally seal thepre-stent member 110, such as by cauterization (melting the stentmaterial) or mechanically sealing, to prevent the fluid or fillermaterial from leaking from the proximal end of the pre-stent member 110.

Once the pre-stent member 110 is expanded and sheared, if the expandablemember 120 has been used, the expandable member 120 is maintained in itsexpanded state a sufficient amount of time to allow the pre-stent member110 to cure or harden. (See FIG. 8E). Curing or hardening may resultfrom passage of a sufficient amount of time to allow the fluid or fillermaterial 140 and the pre-stent member tubes 162 to harden by itself, orcuring may be facilitated by a curing mechanism. For example, thepre-stent member material may be of a type that is caused to transforminto a rigid, resilient material due to the stress incurred during theballoon expansion step. The pre-stent member may also harden aftersufficient time has passed after the expansion step. Curing may befurther facilitated by exposure to a heating or cooling medium deliveredinto the expanded balloon or other vessel. Alternatively, an energysource may be used to transmit ultraviolet, radio frequency, microwave,laser, or other energy to the pre-stent member to cause it to cure afterdeployment. For example, one of the curing mechanisms described above inrelation to FIGS. 5A-C may be utilized to cure the pre-stent memberafter deployment. In either case, the pre-stent member 110 is allowed orcaused to cure such that the resulting stent has sufficient radialstrength and resilience to perform the desired stent scaffoldingfunction.

After the pre-stent member 110 has been allowed or caused to harden, theexpandable member 120 (where used) may be contracted and retractedinside the outer sheath 24. The catheter 20 may then be relocated toanother treatment site and the procedure repeated for deployment ofanother stent 84, or the catheter 20 may be completely withdrawn.

FIGS. 9A-C illustrate alternative embodiments of inflatable pre-stentmembers 110 suitable for use in the apparatus and methods describedabove in relation to FIGS. 7A-B and 8A-E. The first embodiment, shown inFIG. 9A, comprises a generally cylindrical member having a cylindricalinternal wall 112 and a cylindrical external wall 114, with the internalwall having a smaller diameter than the external wall. A fluid fillerlumen 118 is provided between the internal and external walls to receivea fluid or filler material during deployment of the pre-stent member. Aplurality of ports 180, such as pinholes, are provided on the externalsurface of the external wall 114 of the pre-stent member 110. The portsare provided to facilitate transmission of therapeutic materials, suchas drugs, that may be provided in the filler or fluid 140.

FIG. 9B illustrates a coil-shaped pre-stent member 110 comprising asingle tube 190 formed in the shape of a coil. The tube 190 is providedwith a fluid lumen 192 for injecting the fluid or filler material 140during deployment of the pre-stent member. The coil may be partially orfully radially self-expanding, radial expansion may be partially orfully obtained by injecting the fluid or filler material 140 through thelumen 192, or the coil may be partially or fully expanded using anexpandable member 120, such as a balloon. Although not shown, thecoil-shaped pre-stent member may also be provided with ports, such aspinholes, to facilitate transmission of therapeutic materials containedin the filler or fluid.

FIG. 9C illustrates a portion of a tubular lattice 160 that may be usedto form a pre-stent member 110. The tubular lattice 160 shown in FIG. 9Cincludes a first pair of parallel tubes 162 a that intersect a secondpair of parallel tubes 162 b, the first and second pair of tubes beingperpendicular to each other. The lattice 160 defines a diamond-shapedvoid space 164 between the pairs of tubes. As described above, othergeometric patterns are also possible using the tubular-shaped membersshown in this embodiment. Each of the tubes 162 includes a fluid lumen163 suitable for injecting a fluid or filler. The fluid lumens 163 ofeach tube intersect the fluid lumens 163 of perpendicular tubes atintersections 165 that are also open to fluid communication. As with theembodiments illustrated in FIGS. 9A-B, the tubes 162 forming the tubularlattice 160 may also be provided with ports 180, such as pinholes, tofacilitate transmission of therapeutic materials contained in the filleror fluid.

A tubular lattice such as that illustrated in FIG. 9C and othercylindrical patterns of tubular elements may be formed in various ways.In one exemplary method, a polymeric double-walled cylindrical tube likethat shown in FIG. 9A is placed on a rotatable mandrel. A laser,preferably mounted on a servo-controlled X-Y positioner, is then used tomelt or heat bond selected regions of the double-walled tube in adesired pattern to create an interconnected lattice of hollow elementsor struts. The regions of the tube between the hollow elements may thenbe cut or melted away by the laser. For example, the laser could bedirected to form a plurality of diamond-shaped patterns where the innerand outer walls of the tube are melted together. The regions of the tubewithin each diamond are then cut out, leaving a criss-cross pattern ofinterconnected hollow struts similar to that shown in FIG. 9C. Ofcourse, prior to introduction of liquid stent material, each strut wouldnot have a cylindrical cross-section as shown, but would instead haveflat inner and outer walls joined together at their edges.

Turning to FIGS. 10A-C, the distal portion of another alternative stentforming and deployment apparatus and its method of use are illustrated.This alternative apparatus and method include use of another form of aninflatable tubular pre-stent member 110 that is able to be formed atselected lengths and deployed at a treatment site, for example, within ablood vessel. The apparatus includes an outer sheath 24 disposed over aninflatable tubular pre-stent member 110. An internal shaft 26 isprovided. An optional middle shaft 150 may also be provided beneath theouter sheath 24 and above the inflatable pre-stent member 110. A taperednosecone 28 composed of a soft elastomeric material to reduce trauma tothe vessel during advancement of the device, is fixed to the distal end29 of the device 20. An optional proximal isolation balloon 70 (notshown) may be included on the external surface of the outer sheath nearthe distal end of the outer sheath.

The outer sheath 24 includes a cutting mechanism 130 at its distal end,preferably on the internal or distal end surface of the outer sheath 24.The cutting mechanism 130 may comprise a mechanical cutter such as acutting blade, a heating element, an electrode, an electrolytic cutter,an ultrasonic cutter, a chemical cutter, or some other mechanismsuitable for shearing, cutting, melting, or separating portions of thetubular pre-stent member 110. The cutting mechanism may be actuated by acontrol member on the proximal handle 40, or it may operate passivelywhen contacted by the pre-stent member 110 during expansion. In the caseof an electrode, electrolytic, ultrasonic, or heating element, theelement or electrode is conductively connected to an energy sourceassociated with the proximal handle 40 in a conventional manner.

The outer sheath 24 and optional middle shaft 150 are preferably formedof conventional catheter tubing having sufficient strength andflexibility to navigate the patient's vasculature, and also to restrictinflation of the portion of the inflatable pre-stent member 110 coveredby the outer and/or middle sheath. Examples of suitable materialsinclude fiber reinforced polymers, particularly polyurethane.

The tubular pre-stent member 110 is a generally tubular structure thatis relatively soft and pliable. The distal end of the pre-stent member110 is attached to the internal shaft 26 at a point near the proximalend of the nosecone 28, and the pre-stent member 110 extends proximallyfrom that point beneath the outer sheath 24. Preferably, the pre-stentmember 110 is formed of a polymer material, a metal or metal alloy, or ablend of two or more of these materials. Examples of suitable materialsinclude the fluid stent materials described above in relation to thedelivery catheters illustrated in FIGS. 2A-F, 3A-F, 4A-D, and 5A-C.

The internal shaft 26 extends beneath the pre-stent member 110proximally from near the distal end of the catheter. The internal shaft26 is provided with a plurality of emitters 110 that are connected to anenergy source (not shown) at the proximal end of the catheter. Theenergy source may be a source of ultraviolet, radio frequency,microwave, laser, or any other energy suitable for curing a materialused to form the pre-stent member 110. For example, the pre-stent membermaterial may be of a type that more readily cures when exposed to aparticular source of energy, or it may include an appropriate curinginitiator that is susceptible to a particular source of energy, in whichcase the energy type and source is selected to be paired with theparticular stent material being used. Several examples of materials,energy types, and combinations thereof are described, for example, inU.S. Pat. No. 6,039,757, which is incorporated herein by reference.Alternatively, the stent material may comprise, may include, or may becoated with a radiation-absorbing material that is expandable followingexposure to radiation, as described in U.S. Pat. No. 6,607,553, which isincorporated herein by reference. Alternatively, the pre-stent membermaterial may be infused or coated with a curing material, such as anultraviolet curable polymer, that facilitates curing of the stentmaterial when exposed to the particular energy source. Severalcombinations of energy and material suitable for these purposes arepossible, as will be readily understood by a person of skill in the art.

Turning to FIG. 10A, the catheter 20 is delivered to a location withinthe blood vessel 60 having a lesion 62 or other defect requiringtreatment. The distal portion 29 of the catheter is advancedsufficiently that the distal tip 28 is distal of the treatment site. Theouter sheath 24 is then retracted to expose the inflatable pre-stentmember 110. The longitudinal distance that the outer sheath 24 isretracted determines the length of the pre-stent member 110 thatultimately will be deployed.

Once the outer sheath 24 is retracted, the pre-stent member 110 isinflated by injecting an inflation medium into the pre-stent member 110by way of either an annular lumen 200 between the pre-stent member 110and the internal shaft, or by an inflation lumen located in the internalshaft 26. In either case, the inflation lumen is in fluid communicationwith a source of inflation medium at the proximal handle 40. Inflationof the pre-stent member 110 causes the pre-stent member to expandbetween the distal point that the pre-stent member is attached to theinternal shaft 26, and the proximal point at which inflation isrestricted by the outer sheath 24 (or middle sheath 150, where present).Expansion of the pre-stent member 110 causes the pre-stent member toconform to the internal surface 61 of the blood vessel 60 at thetreatment location.

As shown in FIG. 10A, after the pre-stent member 110 has been expanded,the emitters 100 emit energy “E” radially outward from their locationson the internal shaft 26 to impinge on the pre-stent member 110. After asufficient amount of energy is emitted to cause the pre-stent materialto cure (or to hasten curing), the energy emission is stopped.

After curing, the fluid used to inflate the pre-stent member 110 iswithdrawn by suction on the fluid delivery lumen in the catheter. Thepre-stent member 110 is then cut using the cutting mechanism 130 on theouter sheath 24. The outer sheath 24 is advance distally until itencounters and cuts the proximal end of the pre-stent member 110. (SeeFIG. 10B). The outer sheath 24 is then advanced further distally,internally of the pre-stent member 110, until the outer sheath 24encounters and cuts the distal end of the pre-stent member 110,detaching it from the internal shaft 26. (See FIG. 10C). After cutting,the catheter 20 may be withdrawn.

The prostheses described herein in each of the above embodiments mayalso be combined or used in conjunction with other stent structures. Forexample, the prostheses described herein may be formed and delivered toa treatment location already having a metallic stent, or simultaneouslywith another metallic or other stent, in order to provide additionalscaffolding, to deliver therapeutic materials contained on or in theprosthesis, or other functions. In several embodiments, a biodegradablematerial may be used to form a prosthesis that is used in conjunctionwith a pre-existing metallic or other more permanent stent, such thatthe metallic or more permanent stent remains in place after thebiodegradable prosthesis has been absorbed or otherwise degraded.

In addition, in each of the embodiments described herein, the prosthesismaterial may be combined with a drug or other therapeutic agent thatinhibits restenosis, reduces thrombus formation or has other therapeuticeffects. The drug or agent may be mixed with the prosthesis material andintroduced with it to form the prosthesis, or the drug may be introducedinto the isolated region separately from the prosthesis material, eithersimultaneously, before, or after introduction of the prosthesismaterial. For example, the prosthesis material and drug could beintroduced in an alternating fashion so that the prosthesis has asandwich structure with separate layers of drug and prosthesis material.Examples of drugs that may be included in the foregoing structuresinclude taxol, rapamycin, analogs of rapamycin such as Everolimus,Biolimus A9, or ABT 578, thrombolytics such as heparin, as well as VEGF,gene therapy agents, and a range of other agents known to those ofordinary skill in the art.

The preferred embodiments of the invention are described above in detailfor the purpose of setting forth a complete disclosure and for the sakeof explanation and clarity. Those skilled in the art will envision othermodifications within the scope and spirit of the present disclosure.Such alternatives, additions, modifications, and improvements may bemade without departing from the scope of the present invention, which isdefined by the claims.

What is claimed is:
 1. A method of forming a prosthesis in a targetvessel of a patient comprising: introducing a distal portion of acatheter to the target vessel, the catheter having a pliable tubularmember comprised of a polymer and disposed within the catheter, wherethe tubular member has a continuous and smooth outer surface along itslength; exposing a portion of the pliable tubular member such that anexposed portion of the tubular member maintains a smooth and continuousattachment with an unexposed portion and further forms a length of theprosthesis to match a lesion length being treated; separating theexposed portion of the pliable tubular member along the continuous outersurface from a remaining portion of the pliable tubular member; andcuring the exposed portion of the pliable tubular member so as to hardenthe exposed portion in the vessel from a soft, pliable state.
 2. Themethod of claim 1, further comprising: expanding the exposed portion ofthe pliable tubular member using an expandable member carried on thedistal portion of the catheter.
 3. The method of claim 1, wherein saidseparating step comprises cutting the pliable tubular member using acutting member carried on an outer sheath disposed on the catheter. 4.The method of claim 3, wherein said cutting member comprises amechanical cutter, an electrolytic cutter, an ultrasonic cutter, achemical cutter, a laser cutter, an optical cutter, an electrode, or aheating element.
 5. The method of claim 1, wherein an outer sheath ofsaid catheter is retracted a sufficient distance to expose the exposedportion of the pliable tubular member.
 6. The method of claim 1, whereinexposing further comprises adjusting the length of the exposed portionof the pliable tubular member so as to have a sufficient length to spana treatment location of the target vessel.
 7. The method of claim 1,wherein said curing step comprises: applying ultraviolet, radiofrequency, laser, infrared, or microwave energy to the pliable tubularmember.
 8. The method of claim 1, further comprising: repeating theforgoing method steps at another location in the target vessel or inanother target vessel.
 9. The method of claim 1, further comprisingdelivering a fluid into a lumen in the pliable tubular member before theseparating step, the fluid solidifying during the hardening step. 10.The method of claim 1, further comprising repeating the forgoing methodsteps at another location in the target vessel or in another targetvessel.
 11. A method of forming a prosthesis in a target vessel of apatient comprising: introducing a distal portion of a catheter to thetarget vessel, the catheter having a pliable tubular member comprised ofa polymer and disposed within the catheter, where the tubular member hasa continuous and smooth outer surface along its length; exposing aportion of the tubular member such that an exposed portion of thetubular member maintains a smooth and continuous attachment with anunexposed remaining portion and; separating the exposed portion alongthe continuous outer surface from the remaining portion to form a lengthof the prosthesis to match a lesion length being treated; expanding theexposed portion of the tubular member into contact against the vessel;and curing the exposed portion of the tubular member so as to transitionthe exposed portion between a soft, pliable state and a hardened state.12. The method of claim 11, wherein said expanding step comprisesexpanding the exposed portion using an expandable member carried on thedistal portion of the catheter.
 13. The method of claim 11, wherein saidseparating step comprises cutting the tubular member using a cuttingmember carried on an outer sheath disposed on the catheter.
 14. Themethod of claim 13, wherein said cutting member comprises a mechanicalcutter, an electrolytic cutter, an ultrasonic cutter, a chemical cutter,a laser cutter, an optical cutter, an electrode, or a heating element.15. The method of claim 11, wherein an outer sheath of said catheter isretracted a sufficient distance to expose the exposed portion of thetubular member.
 16. The method of claim 11, wherein exposing furthercomprises adjusting the length of the exposed portion of the tubularmember so as to have a sufficient length to span a treatment location ofthe target vessel.
 17. The method of claim 11, wherein said curing stepcomprises applying ultraviolet, radio frequency, laser, infrared, ormicrowave energy to the tubular member.